ASME PCC-1:2000 pdf free download – CUIDELINES FOR PRESSURE BOUNDARY BOLTED FLANGE JOINT ASSEMBLY
6 INSTALLATION OF GASKET
Place a new gasket in position after determining the absence of unacceptable imperfections or damage.
(a) Verify that the gasket complies with the dimen- sional (OD, ID, thickness) and material specifica- tions.
(b) Position the gasket to be concentric with the flange ID, taking suitable measures to ensure that it is adequately supported during the positioning process. No portion of the gasket should project into the flow path.
(c) Ensure that the gasket will remain in place during the joint assembly process; a very light dusting of spray adhesive on the gasket (not the flange) may be used. Particular care should be taken to avoid adhesive chemistry that is incompatible with the process fluid or could result in stress corrosion cracking or pitting of the flange surfaces. Do not use tape strips radially across the gasket to hold it in position. Do not use grease.
7 LUBRICATION OF “WORKING” SURFACES
With one exception, liberally coat all internal and external thread surfaces and nuvwasher faces with appropriate lubricant; the exception is: lubricant is not to be applied to these ”working” surfaces for the initial tightening of new, coated bolrs/nuts [see Note (3) of Table lM/Table 11. The torque values for new, coated bolts/nuts shown in Table 1 M/Table 1 do not consider lubrication other than that provided by the bolthut coating [see Note (2) of Table 1 M/ Table 11. Do not apply lubricant to the gasket or gasket-contact surfaces.
(a) Ensure that the lubricant is chemically compat- ible with the bolt/nut/washer materials and the pro- cess fluid. Particular care should be taken to avoid lubricant chemistry that could result in stress corro- sion cracking.
(b) Ensure tha the lubricant is suitable for the expected service temperature(s).
8.2 Bolt Lengths
Check bolts for adequate length. Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code (1998 Edition, 1999 Addenda) requires that nuts engage the threads for the full depth of the nut (see para. UG-1 3). The ASME B31.3, Process Piping Code (1999 Edition), has a similar provision but considers the nut to be acceptably engaged if the lack of complete engagement is not more than one thread (see para. 335.2.3). See para. lO.l(c) of this document if use of hydraulic bolt tensioners is planned.
8.2.1 Corrosion of excess threads can hinder joint disassembly. A practice that facilitates joint disassem- bly (see para. 15) is to fully engage the nut on one end (no bolt projection beyond the nut) so that all excess threads are located on the opposite end; the excess threads should not project more than 1 3 mm (’/2 in.) beyond the nut, unless required for the use of hydraulic bolt tensioners.
10 TIGHTENENING OF BOLTS
Using the selected tightening method/load-control technique (see para. lO.l), tighten the joint using the torque increment rounds shown in Table 2 and the cross-pattern tightening sequence as described in para. 11 .
NOTE: When hydraulic bolt tensioners are employed, use the procedure recommended by personnel who are experienced and qualified in controlled bolting services. Guidelines on use of bolting services contractors are provided in Appendix G.